The four-mile round trip hike starts above the amphitheater at 'Theater-in-the-Pines" in Aspen Grove. The trail is well marked and easy. This was a great early summer hike because everything is so green as I hiked through aspen groves, ferns, oak brush and a few mountain meadows.
There was still quite a few patches of snow melting which created a number of cascades and impromptu waterfalls beside the actual Stewart Falls.
There are some excellent directions and a better hike overview here and here.